Whats tahm kench's problem with yordless???

Something relating to catfish and hair balls, I suspect.

Or Yordles are so cheerful they don't ever make deals with demons.

because they are the demons

They might be too pure for him to corrupt.

Thats why Veigar and Amumu aren't listed(if amumu is a yordle),because both have been broken by their experiences.

I remember that someone from riot also said that all yordles met him once,so maybe there is a more direct relation.

Given how Yordles are these friendly community driven people, Tahm's greed and selfishness might just rub them the wrong way.

Alternatively, consider for a moment we only know Tahm Kench from the perspective of his Bilgewater form. As we've seen with the Shadow Isles champs with Bloodmoon skins, different cultures see these monsters of the world differently. It's almost a certainty that the way Tahm Kench appears in Yordle folklore is very different from the story we've heard.

is not listed

This means that Riot no longer treats him as a yordle?

EDIT: I just noticed that isn't listed either... So maybe Amumu is still a yordle, and the fact that he isn't listed may not mean much since Veigar isn't listed, and he is clearly a yordle. However, Veigar is evil, which maybe is the reason why he isn't listed.

Well, when after carrying an allied Yordle... I can't imagine the leftover woodchips being too appetizing.

lol

They are not rivals, it just means that every yordle has encountered inner demons like him or just like him.

Well, dam. XD

They are small and bite sized.

Just another reason to buy him. I hate yordles too.